$toolbar-size: 52px;
/*定义函数*/
@mixin toolbar-item($pos,$hoverPos){
    background-position: -1px $pos;
    &:hover{
         background-position: -1px $hoverPos;        
    }
}

.toolbar{
    position: fixed;
    left: 50%;
    bottom: 30%;
    margin-left: -$toolbar-size / 2;
}
.toolbar-item{
    display: block;
    width: $toolbar-size;
    height: $toolbar-size;
    margin-top: 1px;    
    position: relative;
    transition: all 1s;
    
}
